Rotary heat exchanger, in particular for a gas turbine

ABSTRACT

A disc of porous ceramic material is coupled to a metallic rim having gear teeth for rotation therewith by means of a plurality of intermediate split annular metal collars. The collars are resiliently clamped to an asbestos packing ring surrounding the periphery of the disc. A connecting link is tangentially disposed relative to each collar and pivotally connected to one end of each collar at one end and to the rim at the other end.

United States Patent [1 1 Guillot May 13, 1975 [5 ROTARY HEAT EXCHANGER, IN 3,74l,287 8/1973 hllittman .ml 165/8 E 3,766,972 1 1973 ltano eta... PARTICULAR FOR A GAS TURBIN 3,789,917 2/1974 Jarry [65/8 [75] Inventor: Jack Guillot, Juvisy-sur-Orge,

France Primary Examiner-Albert W. Davis, Jr. [73] Asslgnee' Ri a g f Smut-Blane Attorney, Agent, or FirmSughrue, Rothwell, Mion,

o e a Ce Zinn & Macpeak [22] Filedi Oct. 15, 1973 [21] Appl. No.: 406,419

[57] ABSTRACT 30 F A'l't' r11): 1 O l 52 pglca y a a A disc of porous ceramic material is coupled to a me- Ct. rance im ing g r tee fo atio here th means of a plurality of intermediate split annular [52] 165/8 64/27 1 metal collars. The collars are resiliently clamped to an 51 I Cl Fzsd 00 Y asbestos packing ring surrounding the periphery of the f 443 g disc. A connecting link is tangentially disposed rela- 1 o earc l tive to each collar and pivotally connected to one end 7 27 1 I I of each'co llar atone end and to the rim at the other [56] References Cited UNITED STATES PATENTS 8/1970 Horton 165/8 X I 5 Claims, 5 Drawing Figures PATENTED HAY 1 3M5 3,882,926

sum 10F 3 S'HEH 2B. 3

PATENTEU MAY 1 W5 PATENTED HAY 1 31975 882,926

1 ROTARY HEAT EXCHANGERJN PARTICULAR FOR A GAS TURBINE The present invention relates to a rotary heat exchanger of a new type, intended to be fitted, for instance, to a gas turbine.

It is known to make the heat exchanger as a disc of porous ceramic material mounted within a "metallic rim, the latter having outer tooth with which one or more driving pinions mesh.

In practice, some difficulty is encountered in ensuring the connection between the ceramic disc and the metallic rim. As a matter of fact, the brittleness of the porous ceramic material does not allow driving the disc from a central hub. On the other hand, a drive from a peripheral rim creates a problem, due to the high difference between the coefficients of expansion of ceramic and steel. In fact, the coefficient of expansion of the steel constituting the rim is about l.2 X while the coefficient of expansion of ceramic is zero, and is even slightly negative beyond 500C. Consequently, on an exchanger disc having a diameter of about forty centimetres, differences in expansion of about 2 millimetres as regards the diameter may be observed, depending on the operating conditions for the turbine.

It is found that the arrangements known heretofore for ensuring the connection between the steel rim and the periphery of the ceramic disc show the two following major drawbacks:

first of all, in general it is necessary to machine transverse receases in the periphery of the ceramic disc, which receases are intended for housing the connecting and driving members for the rim: such a mechining on porous ceramic is a very difficult and highly expensive operation;

on the other hand, localized stresses occur in the ceramic, at the bottom of the receases, so that, in use, cracks appear progressively, which lead to the destruction of the exchanger disc.

The object of the present invention is to obviate such drawbacks by providing an exchanger disc, the porous ceramic central part of which remains perfectly centered within the metallic rim at all times, whatever may be the operating temperatures. It makes it posssible, besides, to manufacture the exchanger at a comparatively low cost.

A rotary exchanger according to the invention includes a porous ceramic disc housed within a metallic toothed annulus, and is characterized in that the ceramic disc has an iniform circular periphery over which a layer of a refractory but deformable material, such as asbestos, is clamped by a plurality of collars disposed side by side over the thickness of the disc but annularly offset with respect to each other, each collar having an anchoring point for one of the ends of a metallic connecting member, the other end of which is anchored to the inner wall of the toothed annulus, so that the connecting members are distributed around the disc and extend obliquely within the annular space defined between the outer surface of the disc and the inner surface of the toothed annulus.

According to a further feature of the invention, resilient means are provided to ensure the clamping of each collar on the layer of asbestos or the like material. Such means may include the two ends of the collar, which are bent outwardly opposite each other, while a clamping bolt passes through these two ends, the nut of said bolt bearing on a pile of resilient washers bearing in turn upon the corresponding bent end of the collar, so that any variation in the diameter of the ceramic disc causes the compression of the pile of resilient washers to vary.

According to a preferred embodiment of the invention, nine collars are disposed side by side over the thickness of the ceramic disc, these collars corresponding thus to nine anchoring members on the toothed annulus. The fixing points of the ends of each anchoring member may be pivotally mounted. With this arrangement, it will be seen that the expansions can take place freely when a change of temperature occurs, the ceramic disc rotating them slightly in one direction or the other inside the toothed annulus, while remaining securately centred within said annulus.

The rotation of the ceramic disc is brought about by the clamping action of the collars on the asbestos or the like packing.

The attached drawing, given by way of non-limiting example, will enable the features of the invention to be FIG. 3.

FIG. 5 is a perspective view illustrating the relative positions of three juxtaposed clamping collars.

The heat exchanger according to the invention comprises a flat disc 1, made of a ceramic material having a porous or cell-like structure known which is well known in the art. This structure enables a liquid or gaseous fluid to pass from one side of the disc 1 to the other, while passing through the thickness of the latter. The ceramic material used has a coefficient of expansion which is zero, or even negative.

It will be noted that the disc 1 according to the invention is perfectly cylindrical, that is, it is not necessary to machine any notch in its periphery.

The ceramic disc 1 is mounted within a peripheral rim or annulus 2 of steel. This annulus has outer tooth 3, which are used to rotate the exchanger.

According to the invention, a layer 4 of a flexible refractory material, such as asbestos, is applied onto the cylindrical periphery of the disc 1. Juxtaposed collars 5, 6, 7 are clamped over said layer or strip 4. Each collar has at each of its opposite ends a turned up edge 8, 9, which edges face each other and are clamped together by screwing screws 10 into edge 8 (FIG. 4). On the other hand, resilient washers 12, such as Balleville washers, are piled between each screw head 11 and the corresponding turned up edge 9. Thus, once the collar 5 is clamped, the various possible contractions or expansions enable the two turned up edges 8, 9, to slightly draw away from each other or nearer to each other, while the clamping action is maintained by the resilient washers 12.

The turned up edge 8 is provided with a transverse pivot pin 13 connected to the toothed annulus .2 through a connecting member 14 hinged to said annulus. To this end, the annulus 2 is preferably given a U- shaped cross-section (FIGS. 1 and 4), both limbs of the U being directed towards the disc 1. Two headless screws 15, which are screwed opposite each other through apertures 16 in the limbs of the U formed by the annulus 2, constitute materially the hinge axis to which the connecting member 14 is linked.

The collars such as 3, 6, 7 may be, for instance, nine in number. It will be seen in FIGS. 1, 2 and that these collars are angularly offset evenly with respect to one another, so that the pairs of turned up edges 8, 9, are evenly distributed all around the periphery of the disc 1. Each pair of turned up edges 8, 9, are connected to the annulus 2 through a hinged connecting member 14. Thus, it will be seen that the connecting members 14 are distributed between the disc 1 and the annulus 2 in a way fairly similar to the arrangement of the spokes of a bicycle wheel between a hub and a rim. Such an arrangement has three major advantages, namely:

a. it takes up very little space, as the members 8, 9 and 14 can be practically housed within the U formed by the annulus 2 (FIG. 2);

b. the action of the differential expansions between the steel material of the annulus 2 and the ceramic material of the disc 1 brings about a mere relative rotation of the disc 1 withinthe annulus 2,according to an am plitude which is, very small and which does not prevent the disc 1 from being accurately centred within said annulus 2;

c. as previously mentioned, it is possible to use a ceramic disc 1 in the raw state, that is, without any machining of notches or recesses intended for securing various members.

I claim:

1. A rotary heat exchanger comprisinga disc of porous ceramic material having a uniform circular peripheral surface, an annular layer of deformable refractory material disposed about the periphery of said disc, a plurality of split annular collars disposed about said rewardly bent ends of'said collars.

fractory material in side by side relation, clamping means engaging the ends of said collars for clamping said collars and said refractory material to the periphery of said disc, an annular gear ring surrounding said collars in radially spaced relation thereto and link means pivotally interconnected between said collars and said gearing whereby rotary motion imparted to said gear ring would be transmitted through said link means, said collars and said refractory material to said disc.

2. A rotary heat exchanger as set forth in claim I wherein said clamping means includes resilient means to compensate for the expansion and contraction of said collars.

3. A rotary heat exchanger as set forth in claim 2 wherein the opposed ends of each collar are bent radially outwardly opposite each other in spaced relation, said clamping means is comprised of bolt means threadedly secured in one of said outwardly bent ends while freely extending through an aperture" in the other of said outwardly bent ends and said resilient means is comprised of a plurality of resilient washers interposed" between the head of said bolt and the other of said out- 4. A rotary heat exchanger as set forth wherein nine split annular collars are disposed in side by side relation with the split portion of each of said collars being equally spaced about the periphery of said disc.

5. A rotary heat exchanger as set forth in claim 3,

wherein said link means is pivotally secured at one end to an outwardly bent end of each collar and the other end is pivotally connected to said gear ring so that said link means is tangentially disposed with respect to said collars.

in claim 1 

1. A rotary heat exchanger comprising a disc of porous ceramic material having a uniform circular peripheral surface, an annular layer of deformable refractory material disposed about the periphery of said disc, a plurality of split annular collars disposed about said refractory material in side by side relation, clamping means engaging the ends of said collars for clamping said collars and said refractory material to the periphery of said disc, an annular gear ring surrounding said collars in radially spaced relation thereto and link means pivotally interconnected between said collars and said gearing whereby rotary motion imparted to said gear ring would be transmitted through said link means, said collars and said refractory material to said disc.
 2. A rotary heat exchanger as set forth in claim 1 wherein said clamping means includes resilient means to compensate for the expansion and contraction of said collars.
 3. A rotary heat exchanger as set forth in claim 2 wherein the opposed ends of each collar are bent radially outwardly opposite each other in spaced relation, said clamping means is comprised of bolt means threadedly secured in one of said outwardly bent ends while freely extending through an aperture in the other of said outwardly bent ends and said resilient means is comprised of a plurality of resilient washers interposed between the head of said bolt and the other of said outwardly bent ends of said collars.
 4. A rotary heat exchanger as set forth in claim 1 wherein nine split annular collars are disposed in side by side relation with the split portion of each of said collars being equally spaced about the periphery of said disc.
 5. A rotary heat exchanger as set forth in claim 3, wherein said link means is pivotally secured at one end to an outwardly bent end of each collar and the other end is pivotally connected to said gear ring so that said link means is tangentially disposed with respect to said collars. 